Trifluoroacetic acid → (R)-(1-isopropyl-7-(methylsulfonyl)-1,2,3,4-tetrahydrobenzo[4,5]imidazo[1,2-a]pyrazin-8-yl)methyl acetate

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Reaction Steps

TFA (1 mL) was added dropwise to a solution containing (R)-tert-butyl 8-(acetoxymethyl)-1-isopropyl-7-(methylsulfonyl)-3,4-dihydrobenzo[4,5]imidazo[1,2-a]pyrazine-2(1H)-carboxylate (210 mg, 0.452 mmol) in DCM (5 mL) at rt. The mixture was stirred at rt for 2 h. TLC showed compound 3 was consumed completely. The solvents were removed under reduced pressure at 30° C. and then DCM (10 mL) was added. The mixture was neutralized by sat. NaHCO3 solution to pH=8. The mixture was extracted with DCM (3×20 mL) and the combined organic layers were dried over anhydrous Na2SO4, filtered and concentrated under vacuum to afford (R)-(1-isopropyl-7-(methylsulfonyl)-1,2,3,4-tetrahydrobenzo[4,5]imidazo[1,2-a]pyrazin-8-yl)methyl acetate (160 mg, 97.1% yield) as a white solid, which was used directly for the next step without further purification.

Provenance & Evidence